Help with sebastienm's code - Returning To Previously Selected Worksheet

[AcesUp]

Hi all,

I'm trying to utilise the following code detailed by sebastienm in this
post,

http://www.excelforum.com/showthread.php?t=477940&highlight=worksheet+workbook+returning+previous

However once complete and I have tried to test the Macro the following
error is returned - "Run time error 91 - Object variable or with block
variable not set"

In debug the following piece of code from the second module is
highlighted - "Tracker.GotoLastSheet"

Can anyone help me in working out where I have gone wrong?

I am a relative novice in this area so apologies if it is a obvious
mistake on my half.

Many Thanks in advance,

AcesUp
-
CLASS MODULE-

' ------------------------------------------------------
Option Explicit

Private WithEvents App As Application
Private mLastSheet As Object

'------------------------------------
Public Property Get LastSheet() As Object
Dim s As String
If mLastSheet Is Nothing Then
Set LastSheet = Nothing
Else
On Error Resume Next 'capture automation error if book has been
closed
s = mLastSheet.Name
If Err <> 0 Then
Set mLastSheet = Nothing
Set LastSheet = Nothing
Else
Set LastSheet = mLastSheet
End If
End If
End Property

Public Sub GotoLastSheet()
If Not LastSheet Is Nothing Then
On Error Resume Next 'if hidden book or other error
LastSheet.Parent.Activate
LastSheet.Activate
End If
End Sub
'------------------------------------

Private Sub App_SheetDeactivate(ByVal Sh As Object)
Set mLastSheet = Sh
End Sub

Private Sub Class_Initialize()
Set App = Application
End Sub

Private Sub Class_Terminate()
Set App = Nothing
End Sub
'-----------------------------------------------------

-REGULAR MODULE-

'----------------------------------------------------
Option Explicit
Public Tracker As ClsSheetTracker

Sub GotoLast()
Tracker.GotoLastSheet
End Sub
'----------------------------------------------------